The subscription features were unveiled by Gavri Smith, a Google software engineer, on the Google Inside Search Blog.

"Google Trends is a helpful place to see what people are searching for around the world," wrote Smith. "You can keep up with hot searches in real time, or take a historical look at trends dating back to 2004."

Sometimes, though, it can be tough to find the most interesting and surprising trends out there, wrote Smith. That's where the new subscription tool can help, by providing "just the right insights at just the right time with email notifications," wrote Smith.

Using the new "Subscribe" button, users can get custom search information for any search topic, for Hot Searches for any country, or about any U.S. monthly Top Chart, wrote Smith. "For example, I lived in the U.K. for three years and I wanted a way to quickly and easily keep up with the really big things happening there. I set up an email notification to tell me about the 'hottest' Hot Searches in the U.K. and now I get occasional emails about major local trends—from the London Marathon to Britain's Got Talent."

Users can subscribe to email notifications about searches for any topics they want to follow. If users get carried away and add too many subscriptions, they can edit their choices later and unsubscribe to the searches of their choice.

Google is often refining its search Trends services. In December 2013, Google updated its Google Trends search page with several new features to make it easier for users to find the trend information they are seeking.

The improved Trends page came just after Google released its 13th annual Zeitgeist list of the most popular trending searches for 2013. No. 1 on that list was former South African President Nelson Mandela, followed by searches for the actor Paul Walker and the Apple iPhone 5S. Google releases the Zeitgeist, or "Spirit of the Times," lists and an accompanying Year in Review video each December to highlight the top trending searches by online visitors to Google.com in the past year.

The most obvious change in Google Trends at that time involved its updated home page, which formerly first presented users with the most recent Hot Searches. Now users can go to the Top Charts listings to see what is trending at that moment, while also perusing a far wider range of ongoing trends. Also added to Trends was the ability to search for trends in 72 nations around the world. Previously, only trends in the United States were searchable.

Users also gained the first-time ability to view Hot Searches for 47 countries, up from the 14 that previously were featured.

Google had previously updated Trends in May 2013 when it first added the Top Charts feature to help users keep up with the latest people, places, products and subjects that are trending in Google searches. The lists, which are ranked by search interest by millions of users online, are updated monthly. A wide assortment of more than 40 list categories are featured in Top Charts, including actors, animals, athletes, authors, baseball players, baseball teams, books, cars, cities, colleges and universities, movies, musical artists, politicians, reality shows, retail companies, scientists and more.